# [r-t] Adjacency in Extension

Andrew Johnson andrew_johnson at uk.ibm.com
Sat Jul 28 08:22:28 UTC 2018

```> From: Don Morrison
>
> On Fri, Jul 27, 2018 at 2:19 PM Mark Davies wrote:
>
> > Why shouldn't extension work starting with four bell? There's
> > something wrong with our approach it if doesn't. There are plenty of
> > Treble Dodging Minimus methods, too - including Kent.
>
> Well, a lot of things go, if not “wrong”, certainly “different”,
> when you get down to minimus. The whole (I have argued rather silly,
> though I concede we’re possibly stuck with them now) distinction
> between treble bob, surprise and delight evaporates down there. As
> that class distinction is, presumably, a desired* property to
> preserve across extension it makes things, well, confusing, doesn’t
> it? As you said, perhaps this is yet more evidence that there is
> something wrong with the current approach to extension.
Also considering Oxford Treble Bob Minimus - it is double as well
as false in the plain course (each row twice).
Those characteristics are not preserved, though in general terms
preserving the same symmetry in an extension, and retaining truth
do make the extended method more like the parent.

For amusement, here are some Oxford TB Minimus-like methods:
http://www.ringing.org/method/?notation=x3456x16x1256x16x1234x16%2C16&stage=6
http://www.ringing.org/method/?notation=x345678x18x125678x18x123478x18x123456x18%2C18&stage=8
http://www.ringing.org/method/?notation=x34567890x10x12567890x10x12347890x10x12345690x10x12345678x10%2C10&stage=10

It's not worth forcing extension rules to work down to minimus
to cope with saying Oxford TB minimus extends to minor if it
complicates rules.
Similarly it is a bit silly to say two methods are related because
they both have a non-negative integer quantity 'n' of a certain
characteristic if that number is zero in one of them.

--
Andrew Johnson

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